CA2096873C - Coating composition having improved intercoat adhesion, its use and multi-layer coating composite - Google Patents
Coating composition having improved intercoat adhesion, its use and multi-layer coating composite Download PDFInfo
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- CA2096873C CA2096873C CA002096873A CA2096873A CA2096873C CA 2096873 C CA2096873 C CA 2096873C CA 002096873 A CA002096873 A CA 002096873A CA 2096873 A CA2096873 A CA 2096873A CA 2096873 C CA2096873 C CA 2096873C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
- B05D7/50—Multilayers
- B05D7/56—Three layers or more
- B05D7/57—Three layers or more the last layer being a clear coat
- B05D7/577—Three layers or more the last layer being a clear coat some layers being coated "wet-on-wet", the others not
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
- C09D133/04—Homopolymers or copolymers of esters
- C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09D133/062—Copolymers with monomers not covered by C09D133/06
- C09D133/066—Copolymers with monomers not covered by C09D133/06 containing -OH groups
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/60—Additives non-macromolecular
- C09D7/63—Additives non-macromolecular organic
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Paints Or Removers (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
The present invention provides a coating composition having improved intercoat adhesion with an under coating layer. The coating composition comprising:
(A) a film-forming resin, (B) a crosslinking agent for thermosetting the resin (A), and (C) a phosphate, a sulfonic acid or a carboxylic acid having a long-chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12. A solid content of the component (C) is 0.1 to 5 % by weight based on a total solid content of the components (A) and (B). The use of the coating composition and a multi-layer coating composite are also provided.
(A) a film-forming resin, (B) a crosslinking agent for thermosetting the resin (A), and (C) a phosphate, a sulfonic acid or a carboxylic acid having a long-chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12. A solid content of the component (C) is 0.1 to 5 % by weight based on a total solid content of the components (A) and (B). The use of the coating composition and a multi-layer coating composite are also provided.
Description
COATING COMPOSITION HAVING IMPROVED INTERCOAT ADHESION, ITS USE ANfD MULTI-LAYER COATING COMPOSITE
FIELD OF THE INVENTION .
The presenvt invention relates to a coating composition having :improved intercoat adhesion with an under coat, its use and a mufti-layer coat.
BACKGROUND OF THE INVENTION
In order to protect a metal from corrosion and keep its appearancE~, formation of a mufti-layer coating composite (typically, formed by a coating composition for automobiles) is required on a substrate. In other words, a coating composition having different compositional ingredients and performances is ofte n applied on an under coating layer. In this case, pef~ling of the coating layer often occurs due to deterioration of thc~ adhesion between the under coating layer and the coatin g layer thereon. In order to improve the adnesion zaith the under coating layer, there can be often used a rnethod wherein the under coating layer is sanded. However, workability becomes inferior because the method includes the sanding step.
Further, in the coating process of automobiles, there can be c3enera:Lly used a method which comprises applying a thc~rmose?tting color base coating composition, applying therf~on a thermosetting clear coating composition (hereinafter, merely referred to as "clear coating composition") without baking the thermosetting color base coating composition (so-called "wet-on-wet") and then baking _ 2 _ 20968 73 to cure a color base coat layer and a clear coat layer, simultaneously (parti.cularly, this method is referred to as "two coat-one bake: system"). If some defects occur in the coating surface ~>roduced by the "two coat-one bake system", it is propo~;ed that the coating surface is sanded and then again coated with the same "two coat-one bake system". Howeve:r, in practical automobile coating lines, if some defects occur in the coating surface obtained by the "two coat-one bake system", without sanding the coating ~~urface, the color base coating composition and the clear coating composition are further applied by "two coat-one bake system" on the coating surface having the defects .
Thus, a coating composite sequence is obtained consisting of (i) pri.mer coated substrate, (ii) first base coating layer, (iii) first clear coating layer, (iv) second base coating layer and (v) second clear coating layer is formed. In the actual application, since the base coating composition is different in compositional ingredients from the clear coating composition, the adhesion between a first clear coating layer and a second base coating layer i~; inferior and peeling of the coat often occurs.
In order tc> improve the adhesion, a phosphate compound has been proposed to be contained in the coating composition. For example, in U.S. Patent No. 4,971,841, a phosphoric acid or alkylbenzenesulfonic acid is used for this purpose. However, an alkyl group bonded to the phosphoric acid or alkylbenzenesulfonic acid has 1 to 12 carbon atoms a.nd, further, adhesion to the under coating layer surface is not: necessarily sufficient. The phosphoric acid used in the reference is a free phosphoric acid and is different from a phosphate used in the present invention. In addition, the present invention includes no aromatic in a sulfonic compound.
In L;~. S. Patent No. 4, 772, 289, a phosphate having a polyether chain is used in order to improve adhesion with leather articles. However, the adhesion with the under' coating surface is not necessarily sufficient and. defecas of durability due to ether results.
In L'.S. Patent Nos. 4,839,403 and 4,801,628, it is proposed that a phosphoric acid ester having a hydroxyl grouch prepared from phosphoric acid and an epoxy compound is used for improving adhesion. When this compound is used, adhesion to the metal surface is improved, however, adhesion with a coated surface is not necessarily su.f f iciE:nt .
OBJECTS OF' THE INVENTION
One object: of the invention is to provide a coating composition of which intercoat adhesion with an under coating layer is improved by selecting a specific phosphate or other compound.
BRIEF EXPLANA"fI~JN OF j"7Rl~WTr7C;s Fig. 1 is a schematic sectional view which illustrates a mu:lti -layer coating corvposi.te for both prior ao.:-t and the preser~t~ inven~:iox~
SUMMARY CAF THE :INVENT1QN
According to tlm present. ira.~~~er~tion, there is provided a process for forming a coata.ng composite on a substrate, comprising the step::, of:
forming on the substrate a cured film composed of a first base coat layer arid a first cl~Aaa:~ c°oat layer :formed on the first base coat layer, applying a second base coat~:~.nc~ composition on said cured film without sanding the cured fil~rc, applying a second c~.ear coat_.i.rac~ composition thereon without curing the secc:.~nd base coating composition, arid then baking to cure simultaneously the second base coating composition and tine 5cac:c7nd c~,:l.e;~ar. coating composition, wherein bath said :~cacc:~nd ~~a~.~rva c°oating c~ompo;~ition and first base coating composition which forms said first base coati layer comprises (A) a film-forming resin, (B) a c:rossli.rikinc ac~er~t: fco:.~... trrermosettin~,~ t:he resin (A), and ..
(C') a phosphate, a sul.fonic~ acid or a carboxylic acid having a long---c:hairz al.k~~.l. grc~u~:~ c,~f 8 t:.c> 1S carbon atoms and HLB of 3 to 1.2 , wherein a sal.ic.~l c:.o:rzteni~ of t km-: componerit ( C) formulated is 0.1 t.o 5 ~ 1>y weight based ~.or~ a total solid ec>ntent of the componenr: ,s (A i anc~ ( F-~ j .
Further, the present. iuver~tiorr ~a:l_~7o provides a mul.ti-layer coating composite obtained by true process .
DETAILED I:)ESCRI~'TION O~~ THE INVENTION
The f i 1.m-1 orrri:irzq r~:s in ,_z sect i.n the present:
invention is not specif.icallr limztc:d, and there can be used resins which are normally used fc:;r a therrnosett~img coating composition. Examples ~.herecaf ir~.c:lixde acrylic re:~irr, polyester: resin, alkyd :resin, e~::~oxy res~.n, urethane resin or a mixture thereof . A solvents zas.ed fc:~ ~:he coating composition of the present: i:cxver~.t ~.orn ctoay be an aqueous solvent or an orc~arza..c solvent:.. In t~he~ case of the <aqueous solvent, a water-solubili.zable croup (e. g. carboxyl. or amino group) is ineorpc>rated a.n the f: ~.lm-fc~x:mirs.g resin and the resin is neutrali.zec~ with a neurra:lz.~l.ng agent, whereby, the resin cart be dis~solt~ed ~~rr di~F7E?z.;sed ~..rz water. As thN
preferred resin, for- example, t:~~exc~ ~~.xe acrylic i:es~n, polyester resin and the like. t?arty~_cv.~a.ar:l~T prefe:rrNd one is are acrylic resin prepared from r> to ~(a m by weight of amide group-containing ethylenic monarae:rs (e. g. (meth)acrylamide, N-butyl acrylamide), aci~,i group ccantaining ethylenic monomers (e.c~. (meth)acrylic acid, mal.eic acid and itaconic acid) and other ethylenic° manamer:a (e. g. (meth)acrylates, such as methyl (meth)acry::ate, but~~l (meth)acrylate and 2-hydroxyethyl (meth)acrylate; acry:Lonit.riles; aromatic vinyl monomers, such as st=yrene). :In general, the resin preferably has an hydroxyl value of 20 to 200, mare preferably 30 to 15C). A hydroxyl group is considered to be a reaction site with a crosslinkit~g agent. Further, the film--forming resin preferably has a number-average molecular weight of 1,000 to 50,000, mare preferably 1,000 to 20,000.
The crosslinking agent oj;' the component (B) is required for thermosetting the fii.ixa--forming resir9 (A) .
Examples thereof include blacked pc~l.yisocyanate t:ompounds, alkoxylated melamine-aldehyde condensates (melamine-folmaldehyde), alkoxylated compaunc~s of a candensate with paraformaldehyde (e. g. methoxymethylolmelamine, isobutoxylated methylolamelamine, n-butoxylated methylolmelamine, etc.), a'dicyclic, aromatic or aliphatic epoxy compounds containing at least two epoxy groups [e. g.
Epicoat 828, Epicoat 1d0~., Epi.coat: 1009 (manufactured by ~r~n Shell Chemical C,o.), Epolite DOE, Epcalite 900E, Epolite No.1600, Epolite No.'~21 (manufactured by Kyosei Yushi Co.), etc.) and the like. At least one sort of them may be used.
The component (C) used in the present: invention is phosphate, sulfonic acid or c°arboxylic acid having a long-~o9ss ~3 chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12. The number of carbon atom is preferably 8 to 18. When it is smaller than 8, wettability to the coating layer is deteriorated, which results in inferior intercoat adhesion. When it exceeds 18, the component (C) is crystalized in the coating composition and it is not preferred. More preferably, the number of carbon atoms is 10 to 14, whereby, wettability becomes good and intercoat adhesion is improved. HLB of the compound is represented by Gliffin equation:
HLB = 20 (MH/M) wherein MH is a molecular weight of a hydrophilic part and M
is a molecular weight of an activator. A molecular weight of the following phosphate, sulfonic acid or carboxylic acid is used as the molecular weight of the hydrophilic group part. HLB is 3 to 12, preferably 4 to 8. When HLB is not in this range, deterioration of wettability results, and it is not preferred. The compound C is a compound represented b;y the formula:
~ n H 2n+1 0 )m P-( O.H )3_m O n «nH2n+1 0~ P-(0 H)3_m _1I _ 0 n f~ 2n+1 S 0 H , or ~n~~.2n+1000H
i;, _ g _ wherein n is an integer of 8 to 18 and m is 1 or 2, or a salt thereof. More preferred compounds are 2-ethylhexyl acid phosphate, mono- or di-isodecyl acid phosphate, mono-or di-tridecy:L acid phosphate, mono- or di-lauryl acid phosphate, mono- or di-nonylphenyl acid phosphate, lauryl sulfuric acid,, nony:L sulfuric acid, stearic acid, lauric acid and the :Like.
The above component may be formulated as the clear coat composition or it may be formulated with pigments to form a paint. Any bind of pigments, for example, color pigments, extender pigments, metallic pigments, mica particles and the like may be normally used. Examples of the color pigment include carbon black, acetylene black, chrome yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, r~avele~; yellow, benzidine yellow, molybdate orange, permanent orange GTR, red iron oxide, cadmium red, resol red, permanent: red 4R, fast violet B, methyl violet lake, metallic phthalocyanine blue, fast sky blue, chrome green, chrome oxide, titanium oxide and the like. Examples of the extender pigment include barium carbonate, clay, silica, talc and they like. As the metallic pigment, aluminum flake is normally used. Examples of the mica particles include on.e wherein mica particles are encapsulated or coated with metallic oxide, typically iron oxide or titanium oxide.
The solid content of the component B is 5 to 60 0 by weight, prE~ferab:Ly 20 to 40 % by weight, based on the total weight of the components A and B. When the solid content of the' crosslinking agent (component B) is smaller than 5 o by weight, the resin is not completely cured, which results in deterioration of water resistance. Further, when it exceeds 60 % by weight, stabilizing of the coating composition i~; deteriorated. The solid content of the component C i~; 0.1 t:o 5 o by weight, preferably 0.5 to 2 0 by weight, babied on the total solid content of the components A a.nd B. When the solid content of the component C is 0.1 % by weight:, adhesion as the effect of the present invention is deteriorated. On the contrary, when it exceeds 5 % by weight, water' resistance is deteriorated.
In additior.~ to the above components, conventional additives, for example, surface modifier, viscosity inhibitor (e. g. water-insoluble particle, etc.), thicknera antioxidant, UV inhibitor, antifoamer and the like may be formulated. The amount thereof is known to the art.
It is considered that, when the composition of the present invention is applied on a coating layer, the long chain alkyl groups of the component (C) are oriented on on the surface of the under coating layer to improve wettability of the hydrophobic coating layer, whereby, intercoat adhesion with the under coating layer is improved.
The preparation of the coating composition is not specifically limited, but the component C is normally added after the components A and B are sufficiently mixed. The ~, - 1° - X0968 73 composition of the present invention is diluted with an organic solvent or an aqueous solvent to make a solution having suitable viscosity which is coated by spray coating, dip coating, brush coating and the like, and then the coated article is dried at 100 to 200°C for 10 to 60 minutes.
The bloating composition of the present invention is particularly ;superior in the use as a top coating composition o:E automobiles and is extremely useful for a base coating c~ompos:ition of a "two coat-one bake coating system" for automobiles. If surface defects occur in the "two coat-one bake coating system" comprising applying a base coating c:ompos:ition containing a pigment, applying a clear coating composition thereon without baking and drying and then baking and drying, sufficient adhesion can not be obtained between a f=first base clear coat and a second base clear coat when a conventional base paint is applied without sanding surface defects, followed by application of a clear coating composition, baking and further drying. However, sufficient adhesion can be obtained by using the coating composition of the present invention.
In th.e coating composition of the present invention, adhesion with an under coating layer (no quality of the under coating layer may be considered) is remarkably improved and high intercoat adhesion can be obtained without sanding treatment of the under coating layer.
Further, when two coat-one bake must be conducted again because surface defects occur in the "two coat-one 20~6873 bake coating",, extrcemely excellent adhesion can be obtained without sanding using the coating composition of the present invention as t:he second base coating composition.
EXAMF~ L E S
The following Production Examples, Examples and Comparative E~;:ample~> further illustrate the present invention in detail but are not to be construed to limit the scope thereof. In t:he Production Examples, Examples and Comparative Ex:ample~;, "parts" and " o s "' are by weight unless otherwise stated.
Production Example 1 Synthesis 1. of acrylic resin To a 2 liter reaction vessel equipped with a stirrer, a thermostat and a condenser, methoxypropanol (76 parts) was charged and heated to 120°C. Then, a monomer solution of styrene (15 parts), methyl methacrylate (63 parts), 2-hydroxyethyl methacrylate (48 parts), N-butyl acrylate (117 parts), methacrylic acid (27 parts), acrylamide (30 parts), methoxypropanol (60 parts) and t butylperoxy-2-ethylhexanoate (3 parts) was further added dropwise over 3 hours and stirred continuously for one hour. Further, dimethylethanolamine (28 parts) and deionized water (536 parts) were added to obtain an acrylic resin having a volatile content of 30 o and a number-average molecular weight of 12000. This resin had a hydroxyl value of 70 and an acid value of 58.
Production Example 2 (for iqment aste) Syntr,iesis ;? of acrylic resin According t:o the same manner as that described in Production Example 7. except for using a monomer solution of styrene (24 parts), methyl methacrylate (73 parts), 2-hydroxyethyl methacrylate (48 parts), N-butyl acrylate (117 parts), methacrylic acid (18 parts), acrylamide (20 parts), methoxypropanol (40 parts) and t-butylperoxy-2-ethylhexanoate (3 parts), a copolymer was synthesized.
Further, dimethylethanolamine (19 parts) and deionized water (565 parts) were added to obtain an acrylic resin having a volatile content of 30 o and a number-average molecular weight of 12000. This resin had a hydroxyl value of 70 and an acid value of 40.
Production Example 3 Synthesis 3 of acrylic resin To the same reaction vessel as that used in Production Example l, xylene (350 parts) was charged and heated to 130°C. Then, a monomer initiator solution of glycidyl methacrylate (250 parts), styrene (25 parts), methyl methacrylate (60 parts), N-butyl methacrylate (165 parts) and t-butylperoxy-2-ethylhexanoate (50 parts) was further added dropwise over 3 hours and stirred continuously for 2 hour to obtain an epoxy group-containing acrylic resin having a volatile content of 55 o and a number-average molecular weight of 2500.
Produ~~tion Exam 1e 4 Synthesis of polyester resin a~
-13- 209fi873 To a 2 liter reaction vessel equipped with a stirrer, a thermostat and a condenser, bishydroxyethyl taurin (67 parts), n eopentyl glycol (65 parts), azelaic acid (118 parts), phthali.c anhydride (93 parts) and xylene (27 parts) were charged and heated. Water produced by the reaction was removed by azeotropy with xylene.
The reaction mixture was heated to 190°C over about 2 hours after the beginning of reflux and stirring and dehydration. were continuously conducted until an acid value (corresponding to carboxylic acid) became 72.5, and then cooled to 140°C. With mainta i n; nor a+- i do°r r~,.a", .. r, "
(manufactured by Shell Co.) (157 parts) was added dropwise over 30 minutes and stirred continuously for 2 hours to complete the reaction. Furthermore, dimethylethanolamine (47 parts) and deionized water (1100 parts) were added. The resulting polyester resin had an acid value of 59, a hydroxyl value of 90, a volatile content of 30 % and a number-average molecular weight of 1054.
Production :Example 5 Synthf~sis o:E acrylic resin To the' same reaction vessel as that used in Production Exannple 1,, xylene (700 parts) was charged and heated to 130°C:. Then, a monomer initiator solution of styrene (200 parts), 2-ethylhexyl acrylate (200 parts), hydroxyethyl methacr5rlate (90 parts), methacrylic acid (10 parts), methyl methacrylate (100 parts) and t-butylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 -~;
hours and stirred continuously for 2 hour to obtain an acrylic resin having a volatile content of 45 %, a number-average molecular weight of 5600 and an acid value of 10.
Production Example 6 Synthesis of acrylic resin To the same' reaction vessel as that used in Production Example J., butyl acetate (700 parts) was charged and heated to 130°C. Then, a monomer initiator solution of styrene (200 p,arts), n-butyl acrylate (200 parts), 2-hydroxyethyl methacrylate (90 parts), methacrylic acid (10 parts), methyl methacrylate (100 parts) and t-butylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 hours and stirred continuously for 2 hours to obtain an acrylic resin having a volatile content of 45 0, a number-average molecular weight of 8000 and an acid value of 10.
Produ~~tion Example 7 Synths=sis of acrylic resin To the same reaction vessel as that used in Production Example l, xylene (350 parts) and methoxypropanol (350 parts) were charged and heated to 130°C. Then, a monomer initiator so:Lution of styrene (160 parts), 2-ethylhexyl acrylate (200 parts), hydroxyethyl methacrylate (90 parts), met:hacrylic acid (50 parts), methyl methacrylate (100 parts) and t-but:ylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 hours and stirred continuously far 2 hour to obtain an acrylic resin having a volatile content of 45 %, a number-average molecular weight _~,~, __ -15- 2o~s873 of 5600 and an acid value of 50.
Production Example 8 Pre~~aration 1 of pigment-dispersed paste Acr:~lic resin prepared in Production Example 2 (54 parts), M-1100 manufactured by Cablack Co. (12 parts) and deionized water (1B parts) were subjected to mill dispersion for 3 hours to obtain a pigment paste.
Production Example 9 Pre~~aration 2 of pigment-dispersed paste Acr:~lic resin prepared in Production Example 6 (100 parts) and Maloo ~~-6424 manufactured by Harmon Co. (15 parts) were :subjected to mill dispersion similarly to obtain a pigment paate.
Example 1 Pre~?aration l of aqueous metallic coating composition The acrylic resin of Production Example 1 (170 parts), C-30:3 manufactured by Mitsui Toatsu Chemicals (methylated melamine, solid content: 100 %, 21 parts), aluminum pas~~e (Alpaste~7160N) manufactured by Toyo Aluminum Co. (16.3 parts) and a 50 o xylene solution of lauryl acid phosphate (H7~B: 7.:3) (1.6 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized wai:er and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous metallic coating composition.
f~''~.
16 _ Example 2 Preparation 2 of aqueous coating composition The acrylic resin of Production Example 1 (170 parts), C-30:3 manufactured by M~.tsui ~"oatsu Chemicals (methylated melamine solid content: 100 0, 30 parts), pigment paste M-100 of Production Example 8 (30 parts) and a 50 % xylene solution of stearyl acid phosphate (HLB . 5.5) (2.5 parts) were mixed with stirring by a stirrer.
top coating compocaition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford. cup #4 t;a obtain a.n aqueous coating composition.
Example 3 Preparation 3 of solvent base coating composition The acrylic resin of Production Example 6 (150 parts), U-20N-60 manufactured by Mitsui Toatsu Chemicals Co.
rn~
(butylated melamine), Br:ightcoppe~ manufactured by Marl Co.
(mica, 17 parts), pigment paste Pe~l.indmaloon of 7:~roduction Example 9 (18 parts} and a 50 ~ xylene solution of isostearyl acid phosphate (HLB: 5.~i) (3.2 parts) were mixed with stirring by a stirrer_ An acrylmelamine base coating composition obtained was diluted with a mixture of ethyl acetate and xylene (1:1) and viscosity was adjusted to 30 seconds at 25°C using Ford cup #4 to obtain an acrylmelamine based coating composition.
Example 4 Preparation 4 of aqueous coating composition _1~_ X096873 The F>olyest_er resin of Production Example 4 (180 parts), C-303 manufactured by Mitsui Toatsu Chemicals Co.
(methylated me~lamine~ solid content: 100 0, 25 parts), pigment paste M-1100 of Production Example 8 (16.3 parts) and a 50 o xylene sc>lution of lauryl acid phosphate (HLB:
7.3) (2.5 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous coating composition.
E_ xample 5 Preparation 5 of aqueous metallic coating composition The acrylic resin of Production Example 1 (170 parts), U-20N-60 manufactured by Mitsui Toatsu Chemicals (butylated melamine, 20 parts), a blocked isocyanate compound obtained by blocking isophorone diisocyanate with methyl ethyl ketone (10 parts), aluminum paste (Alpaste 60-600) manufactured by Toyo Aluminum Co. (16.3 parts) and a 50 % xylene solution of 2-ethylhexyl acid phosphate (HLB: 9.2) (2.4 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous metallic coating composition.
Production Example 10 Preparation 1 of clear coating composition The acrylic resin of Production Example 5 (80 parts) and U-~20N-60 manufactured by Mitsui Toatsu Chemicals Co. (butylated melamine, 15 parts) were mixed with stirring by a stirrer.
A acrylmel.amine based clear coating composition obtained was diluted with a mixture of Solvesso 100 and Solvesso 150 (1:l) and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acrylmelamine based clear coating' composition.
Production Example 11 PreF~aration 3 of clear coating composition The acrylic resin of Production Example 7 (500 parts), epoxy group-containing resin of Production Example 3 (100 parts) and a 20 % ethanol solution of tetrabutylamm.onium bromide (7 parts) were mixed with stirring by a stirrer.
An acid epoxy curable based clear coating composition obtained was diluted with a mixture of Solvesso 100 and Solvesso 150 (1:1) and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acid epoxy based clear coating composition.
Production Example 12 Preparation 4 of clear coating composition The acrylic resin of Production Example 5 (50 parts), C-303 manufactured by Mitsui Toatsu Chemicals Co.
(methylated melamine solid content: 100%, 20 parts), a blocked isocyanate compound obtained by blocking isophorone diisocyanate with methyl ethyl ketone (20 parts) and a 5 0 xylene solution of dibutyltin dilaurate (0.6 parts) were mixed with stirring by a stirrer.
An acryl-melamine-isocyanate based clear coating composition obtained was diluted with Solvesso 150 and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acryl-melamine-isocyanate based clear coating composition.
Comparative Example 1 According to the same manner as that described in Example 1 except f or adding ethyl acid phosphate (HLH value:
15.4) in place of lauryl acid phosphate, an aqueous metallic coating composition was obtained.
Comparative Exam 1e 2 According to the same manner as that described in Example 1 excerpt for adding laurylpolyoxyethyl acid phosphate [HLB value of 12.1 (n=4) and HLB value of 13.5 (n=6)] in place of lauryl acid phosphate, an aqueous coating composition was obtained.
Comparative Example 3 According to the same manner as that described in Example 1 excel?t for adding a reaction product of bisphenol A type epoxy resin having a molecular weight of 400 with phosphoric acid in place of lauryl acid phosphate, an aqueous coating composition was obtained.
Comparative Example 4 According to the same manner as that described in Example 1 except for adding a 50 o xylene solution of lauryl acid phosphate (0.1.6 parts), an aqueous coating composition was obtained.
Comparative Example 5 According to the same manner as that described in Example 1 except for adding a 50 g xylene solution of lauryl acid phosphate (16 parts), an aqueous coating composition was obtained.
Exam 1p a 6 Coat forming method ("two coat-one bake" method) A coating composition obtained in Example 1 was air sprayed on a intercoated steel plate which is not subjected to sanding su~:h that a thickness of a dry coat became y. After ;setting for 5 minutes, the coated plate was 15 preheated at 130°C for 5 minutes and a coating composition obtained in P~~oduction Examples 10 to 12 was air sprayed such that a thickness of a dry coat became 40 u. After setting for 7 minutes, the coated plate was dried at 140°C
for 20 minute:>. Adhesion of the obtained coat was evaluated. The combination of the base coat with the clear coat as well as the results of adhesion are shown in Table.
1.
...n, 0 0 0 o c~ 0 0 o c o w a 0 0 0 0 o c. 0 0 0 0 o c a .,, .-, .-~ ..~ .-, ...~ .~ ..-. .~ .~ .--. ~a w ~ ~. w ~ ~ ~ w n~
d O O O O Cwf'1 op 00 O O N ~5.,"
.G O O O O C~ .~ .-1 ~ L
'D .-~ .--~ .-I .--1 .-~
N C
QI
O E
m N
C y~
O O O O .-i cv'I N N N N N O
~.a .--1 .-i .-1 r--i ...~ .--~ .-~ .-1 .--I .-H U N
iJ
..a N ~ d O 0~~ N 4J Gl N C1 O
M r-1 ,-I .-a r1 .-i .~ ,-1 ~ -.-a .-a O n-d O GL GL 0. G. C~ G1 f3. L1 GL 0. .~ t0 ca. E E E E E' E E E E E a E m m ~o w ai co cn m m ~ E ~.~
o x x x x x', x x x x x U w w w w w w w w w w o a~
E
on a G c c c. c G a c a a C O O O O G O O O O O O G
.,..r .,.~ .,..~ .,q .,.~ .,.,~ .,~ .,..~ .,.~ .,.q .,..
iJ L J-1 .N J..1 J-~ 1J L 1J JJ JJ N
0 o a n a a a o 0 0 ~ H
U 'O Tl 'D Tl ~i 'O 'O 'C 'D 'O
O O O O C O O O O O N
Y~ ~ Y~ ~ Y~ ~i ~
c0 Pa GL Aa pa GL C1~ G1 GL W C4 W N
d O G.
U ,~ L
of of 1r m G d OD L
O L C a C ..-1 U
L
O O
G O
O ~p .b .-.~
CL ~ N M wT ~~ .-~ N M v? U'1 N
E y~ m ya O N N CY d a~ d O d N N td U N
U ~ e-1 ~ r-1 .-i .-I .-a ~-1 .-I e-1 J O.
G. CL a. G. p4 GL G. GL G. 0. s.~ 't7 0o E E E E E E E E E E a c L
c m ~a m co ai cc m ca ~ ~a a o 0 x x x x x' x x x x x v v w w w w w w w w w w m ~ ~ b 0 3 ~o a~
v 0. a. a. a. a. 3 .-~
E E E E E a~ a~
a~ 0 0 0 0 0 ~ ~ v m U U U U U ~C m 0.
d 1 0. L C
O
a .--~ C
m d d ~
a a w C, c0 O
0. ~ N M wt u~, ~D t~ 00 O~ O
~i r L
N
d H
Exam~~le 7 Coat forming method A bare coating composition prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was applied on an intercoated steel plate such that a thickness of a dry coat became 15 u. After setting for 5 minutes and preheating at 80°C for 5 minutes, a clear coating composition of Production Examples 10- to 12 was applied on the coated plate such that a thickness of a dry coat became 40 u, followed by setting for 10 minutes. The coated plate was baked at 160°C
for 18 minute~a by a drier to make a test plate.
The test p:Late was recoated with the same base coating compo~~ition and clear coating composition without sanding and baked at. 140°C for 18 minutes to form a two coat-one bake coat consists of 4 layers. Recoat adhesion of the coat was evaluat:ed. The combination of the base coating composition with the' clear coating composition as well as the results of recoat adhesion are shown in Table 2.
....
>~
O
m d O O O O O O O O O O
.c O O O O O O O O O O
O O O a0 ~r1 ~W n c0 a N
1~ O O~ Ov O~ CT .r O
U
d G
0000~-~cVNNNNN
~.-I .-1 .--~ .--~ .--1 ~-~ .-1 .--1 .-H .-i .-~
~.i v ~ ~ U ~y N d 4J N N
m .-a .-r .--i ~ ~a .-a ~ ,~ .-a .-.1 O C1. p. Q. p, ~2, C3. G1 C1 f~ G, 0.EEEE1'-__EEEEE
E m w co ce ~~ ~n <o m m of o x x x x ~~e x x x x x U W W W W W W W W W W
00 C C C G f~ G G G C G
G O O O O O O O O O O
"'~ .r1 .r-I ~.i ..y ..1 .r1 ....a .,..~ .,..~ "-1 JJ 1-~ Y.~ 1J ii 1.J L yJ L y! y1 ~O U U V U U U U U U U
O a a a a :~ a a a a a U 'p ~O 'L7 'C '17 "O '~ 'O 'O 't7 O O O O O O O O O O
i~ Ya S.n y.. f, 1w 1, l, S. la 1a W G.n CL GL C4 G.>~ CL W Pr f1n U
!~
O
a~
m O
(~. .-I N n'W T V1 .--i N t~7 T V1 E
o a> d C~ a~ w d n~
U n--i e-1 v--1 ,~ ~i r-1 r-1 ~ '-1 r-I
FL A» LL GL C1 C1. Q. C1 GL A.
aD E E E E F. E E E E E
G m ~ ~n ~ ca co m x x x x x x x x x x w w w w w w w w w w U Q. GL 41 G1 Q.
O O O O O
m U U U U U
d L1 .~ N cy? ~rwD r~ 00 O~ O
L
m d E~
FIELD OF THE INVENTION .
The presenvt invention relates to a coating composition having :improved intercoat adhesion with an under coat, its use and a mufti-layer coat.
BACKGROUND OF THE INVENTION
In order to protect a metal from corrosion and keep its appearancE~, formation of a mufti-layer coating composite (typically, formed by a coating composition for automobiles) is required on a substrate. In other words, a coating composition having different compositional ingredients and performances is ofte n applied on an under coating layer. In this case, pef~ling of the coating layer often occurs due to deterioration of thc~ adhesion between the under coating layer and the coatin g layer thereon. In order to improve the adnesion zaith the under coating layer, there can be often used a rnethod wherein the under coating layer is sanded. However, workability becomes inferior because the method includes the sanding step.
Further, in the coating process of automobiles, there can be c3enera:Lly used a method which comprises applying a thc~rmose?tting color base coating composition, applying therf~on a thermosetting clear coating composition (hereinafter, merely referred to as "clear coating composition") without baking the thermosetting color base coating composition (so-called "wet-on-wet") and then baking _ 2 _ 20968 73 to cure a color base coat layer and a clear coat layer, simultaneously (parti.cularly, this method is referred to as "two coat-one bake: system"). If some defects occur in the coating surface ~>roduced by the "two coat-one bake system", it is propo~;ed that the coating surface is sanded and then again coated with the same "two coat-one bake system". Howeve:r, in practical automobile coating lines, if some defects occur in the coating surface obtained by the "two coat-one bake system", without sanding the coating ~~urface, the color base coating composition and the clear coating composition are further applied by "two coat-one bake system" on the coating surface having the defects .
Thus, a coating composite sequence is obtained consisting of (i) pri.mer coated substrate, (ii) first base coating layer, (iii) first clear coating layer, (iv) second base coating layer and (v) second clear coating layer is formed. In the actual application, since the base coating composition is different in compositional ingredients from the clear coating composition, the adhesion between a first clear coating layer and a second base coating layer i~; inferior and peeling of the coat often occurs.
In order tc> improve the adhesion, a phosphate compound has been proposed to be contained in the coating composition. For example, in U.S. Patent No. 4,971,841, a phosphoric acid or alkylbenzenesulfonic acid is used for this purpose. However, an alkyl group bonded to the phosphoric acid or alkylbenzenesulfonic acid has 1 to 12 carbon atoms a.nd, further, adhesion to the under coating layer surface is not: necessarily sufficient. The phosphoric acid used in the reference is a free phosphoric acid and is different from a phosphate used in the present invention. In addition, the present invention includes no aromatic in a sulfonic compound.
In L;~. S. Patent No. 4, 772, 289, a phosphate having a polyether chain is used in order to improve adhesion with leather articles. However, the adhesion with the under' coating surface is not necessarily sufficient and. defecas of durability due to ether results.
In L'.S. Patent Nos. 4,839,403 and 4,801,628, it is proposed that a phosphoric acid ester having a hydroxyl grouch prepared from phosphoric acid and an epoxy compound is used for improving adhesion. When this compound is used, adhesion to the metal surface is improved, however, adhesion with a coated surface is not necessarily su.f f iciE:nt .
OBJECTS OF' THE INVENTION
One object: of the invention is to provide a coating composition of which intercoat adhesion with an under coating layer is improved by selecting a specific phosphate or other compound.
BRIEF EXPLANA"fI~JN OF j"7Rl~WTr7C;s Fig. 1 is a schematic sectional view which illustrates a mu:lti -layer coating corvposi.te for both prior ao.:-t and the preser~t~ inven~:iox~
SUMMARY CAF THE :INVENT1QN
According to tlm present. ira.~~~er~tion, there is provided a process for forming a coata.ng composite on a substrate, comprising the step::, of:
forming on the substrate a cured film composed of a first base coat layer arid a first cl~Aaa:~ c°oat layer :formed on the first base coat layer, applying a second base coat~:~.nc~ composition on said cured film without sanding the cured fil~rc, applying a second c~.ear coat_.i.rac~ composition thereon without curing the secc:.~nd base coating composition, arid then baking to cure simultaneously the second base coating composition and tine 5cac:c7nd c~,:l.e;~ar. coating composition, wherein bath said :~cacc:~nd ~~a~.~rva c°oating c~ompo;~ition and first base coating composition which forms said first base coati layer comprises (A) a film-forming resin, (B) a c:rossli.rikinc ac~er~t: fco:.~... trrermosettin~,~ t:he resin (A), and ..
(C') a phosphate, a sul.fonic~ acid or a carboxylic acid having a long---c:hairz al.k~~.l. grc~u~:~ c,~f 8 t:.c> 1S carbon atoms and HLB of 3 to 1.2 , wherein a sal.ic.~l c:.o:rzteni~ of t km-: componerit ( C) formulated is 0.1 t.o 5 ~ 1>y weight based ~.or~ a total solid ec>ntent of the componenr: ,s (A i anc~ ( F-~ j .
Further, the present. iuver~tiorr ~a:l_~7o provides a mul.ti-layer coating composite obtained by true process .
DETAILED I:)ESCRI~'TION O~~ THE INVENTION
The f i 1.m-1 orrri:irzq r~:s in ,_z sect i.n the present:
invention is not specif.icallr limztc:d, and there can be used resins which are normally used fc:;r a therrnosett~img coating composition. Examples ~.herecaf ir~.c:lixde acrylic re:~irr, polyester: resin, alkyd :resin, e~::~oxy res~.n, urethane resin or a mixture thereof . A solvents zas.ed fc:~ ~:he coating composition of the present: i:cxver~.t ~.orn ctoay be an aqueous solvent or an orc~arza..c solvent:.. In t~he~ case of the <aqueous solvent, a water-solubili.zable croup (e. g. carboxyl. or amino group) is ineorpc>rated a.n the f: ~.lm-fc~x:mirs.g resin and the resin is neutrali.zec~ with a neurra:lz.~l.ng agent, whereby, the resin cart be dis~solt~ed ~~rr di~F7E?z.;sed ~..rz water. As thN
preferred resin, for- example, t:~~exc~ ~~.xe acrylic i:es~n, polyester resin and the like. t?arty~_cv.~a.ar:l~T prefe:rrNd one is are acrylic resin prepared from r> to ~(a m by weight of amide group-containing ethylenic monarae:rs (e. g. (meth)acrylamide, N-butyl acrylamide), aci~,i group ccantaining ethylenic monomers (e.c~. (meth)acrylic acid, mal.eic acid and itaconic acid) and other ethylenic° manamer:a (e. g. (meth)acrylates, such as methyl (meth)acry::ate, but~~l (meth)acrylate and 2-hydroxyethyl (meth)acrylate; acry:Lonit.riles; aromatic vinyl monomers, such as st=yrene). :In general, the resin preferably has an hydroxyl value of 20 to 200, mare preferably 30 to 15C). A hydroxyl group is considered to be a reaction site with a crosslinkit~g agent. Further, the film--forming resin preferably has a number-average molecular weight of 1,000 to 50,000, mare preferably 1,000 to 20,000.
The crosslinking agent oj;' the component (B) is required for thermosetting the fii.ixa--forming resir9 (A) .
Examples thereof include blacked pc~l.yisocyanate t:ompounds, alkoxylated melamine-aldehyde condensates (melamine-folmaldehyde), alkoxylated compaunc~s of a candensate with paraformaldehyde (e. g. methoxymethylolmelamine, isobutoxylated methylolamelamine, n-butoxylated methylolmelamine, etc.), a'dicyclic, aromatic or aliphatic epoxy compounds containing at least two epoxy groups [e. g.
Epicoat 828, Epicoat 1d0~., Epi.coat: 1009 (manufactured by ~r~n Shell Chemical C,o.), Epolite DOE, Epcalite 900E, Epolite No.1600, Epolite No.'~21 (manufactured by Kyosei Yushi Co.), etc.) and the like. At least one sort of them may be used.
The component (C) used in the present: invention is phosphate, sulfonic acid or c°arboxylic acid having a long-~o9ss ~3 chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12. The number of carbon atom is preferably 8 to 18. When it is smaller than 8, wettability to the coating layer is deteriorated, which results in inferior intercoat adhesion. When it exceeds 18, the component (C) is crystalized in the coating composition and it is not preferred. More preferably, the number of carbon atoms is 10 to 14, whereby, wettability becomes good and intercoat adhesion is improved. HLB of the compound is represented by Gliffin equation:
HLB = 20 (MH/M) wherein MH is a molecular weight of a hydrophilic part and M
is a molecular weight of an activator. A molecular weight of the following phosphate, sulfonic acid or carboxylic acid is used as the molecular weight of the hydrophilic group part. HLB is 3 to 12, preferably 4 to 8. When HLB is not in this range, deterioration of wettability results, and it is not preferred. The compound C is a compound represented b;y the formula:
~ n H 2n+1 0 )m P-( O.H )3_m O n «nH2n+1 0~ P-(0 H)3_m _1I _ 0 n f~ 2n+1 S 0 H , or ~n~~.2n+1000H
i;, _ g _ wherein n is an integer of 8 to 18 and m is 1 or 2, or a salt thereof. More preferred compounds are 2-ethylhexyl acid phosphate, mono- or di-isodecyl acid phosphate, mono-or di-tridecy:L acid phosphate, mono- or di-lauryl acid phosphate, mono- or di-nonylphenyl acid phosphate, lauryl sulfuric acid,, nony:L sulfuric acid, stearic acid, lauric acid and the :Like.
The above component may be formulated as the clear coat composition or it may be formulated with pigments to form a paint. Any bind of pigments, for example, color pigments, extender pigments, metallic pigments, mica particles and the like may be normally used. Examples of the color pigment include carbon black, acetylene black, chrome yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, r~avele~; yellow, benzidine yellow, molybdate orange, permanent orange GTR, red iron oxide, cadmium red, resol red, permanent: red 4R, fast violet B, methyl violet lake, metallic phthalocyanine blue, fast sky blue, chrome green, chrome oxide, titanium oxide and the like. Examples of the extender pigment include barium carbonate, clay, silica, talc and they like. As the metallic pigment, aluminum flake is normally used. Examples of the mica particles include on.e wherein mica particles are encapsulated or coated with metallic oxide, typically iron oxide or titanium oxide.
The solid content of the component B is 5 to 60 0 by weight, prE~ferab:Ly 20 to 40 % by weight, based on the total weight of the components A and B. When the solid content of the' crosslinking agent (component B) is smaller than 5 o by weight, the resin is not completely cured, which results in deterioration of water resistance. Further, when it exceeds 60 % by weight, stabilizing of the coating composition i~; deteriorated. The solid content of the component C i~; 0.1 t:o 5 o by weight, preferably 0.5 to 2 0 by weight, babied on the total solid content of the components A a.nd B. When the solid content of the component C is 0.1 % by weight:, adhesion as the effect of the present invention is deteriorated. On the contrary, when it exceeds 5 % by weight, water' resistance is deteriorated.
In additior.~ to the above components, conventional additives, for example, surface modifier, viscosity inhibitor (e. g. water-insoluble particle, etc.), thicknera antioxidant, UV inhibitor, antifoamer and the like may be formulated. The amount thereof is known to the art.
It is considered that, when the composition of the present invention is applied on a coating layer, the long chain alkyl groups of the component (C) are oriented on on the surface of the under coating layer to improve wettability of the hydrophobic coating layer, whereby, intercoat adhesion with the under coating layer is improved.
The preparation of the coating composition is not specifically limited, but the component C is normally added after the components A and B are sufficiently mixed. The ~, - 1° - X0968 73 composition of the present invention is diluted with an organic solvent or an aqueous solvent to make a solution having suitable viscosity which is coated by spray coating, dip coating, brush coating and the like, and then the coated article is dried at 100 to 200°C for 10 to 60 minutes.
The bloating composition of the present invention is particularly ;superior in the use as a top coating composition o:E automobiles and is extremely useful for a base coating c~ompos:ition of a "two coat-one bake coating system" for automobiles. If surface defects occur in the "two coat-one bake coating system" comprising applying a base coating c:ompos:ition containing a pigment, applying a clear coating composition thereon without baking and drying and then baking and drying, sufficient adhesion can not be obtained between a f=first base clear coat and a second base clear coat when a conventional base paint is applied without sanding surface defects, followed by application of a clear coating composition, baking and further drying. However, sufficient adhesion can be obtained by using the coating composition of the present invention.
In th.e coating composition of the present invention, adhesion with an under coating layer (no quality of the under coating layer may be considered) is remarkably improved and high intercoat adhesion can be obtained without sanding treatment of the under coating layer.
Further, when two coat-one bake must be conducted again because surface defects occur in the "two coat-one 20~6873 bake coating",, extrcemely excellent adhesion can be obtained without sanding using the coating composition of the present invention as t:he second base coating composition.
EXAMF~ L E S
The following Production Examples, Examples and Comparative E~;:ample~> further illustrate the present invention in detail but are not to be construed to limit the scope thereof. In t:he Production Examples, Examples and Comparative Ex:ample~;, "parts" and " o s "' are by weight unless otherwise stated.
Production Example 1 Synthesis 1. of acrylic resin To a 2 liter reaction vessel equipped with a stirrer, a thermostat and a condenser, methoxypropanol (76 parts) was charged and heated to 120°C. Then, a monomer solution of styrene (15 parts), methyl methacrylate (63 parts), 2-hydroxyethyl methacrylate (48 parts), N-butyl acrylate (117 parts), methacrylic acid (27 parts), acrylamide (30 parts), methoxypropanol (60 parts) and t butylperoxy-2-ethylhexanoate (3 parts) was further added dropwise over 3 hours and stirred continuously for one hour. Further, dimethylethanolamine (28 parts) and deionized water (536 parts) were added to obtain an acrylic resin having a volatile content of 30 o and a number-average molecular weight of 12000. This resin had a hydroxyl value of 70 and an acid value of 58.
Production Example 2 (for iqment aste) Syntr,iesis ;? of acrylic resin According t:o the same manner as that described in Production Example 7. except for using a monomer solution of styrene (24 parts), methyl methacrylate (73 parts), 2-hydroxyethyl methacrylate (48 parts), N-butyl acrylate (117 parts), methacrylic acid (18 parts), acrylamide (20 parts), methoxypropanol (40 parts) and t-butylperoxy-2-ethylhexanoate (3 parts), a copolymer was synthesized.
Further, dimethylethanolamine (19 parts) and deionized water (565 parts) were added to obtain an acrylic resin having a volatile content of 30 o and a number-average molecular weight of 12000. This resin had a hydroxyl value of 70 and an acid value of 40.
Production Example 3 Synthesis 3 of acrylic resin To the same reaction vessel as that used in Production Example l, xylene (350 parts) was charged and heated to 130°C. Then, a monomer initiator solution of glycidyl methacrylate (250 parts), styrene (25 parts), methyl methacrylate (60 parts), N-butyl methacrylate (165 parts) and t-butylperoxy-2-ethylhexanoate (50 parts) was further added dropwise over 3 hours and stirred continuously for 2 hour to obtain an epoxy group-containing acrylic resin having a volatile content of 55 o and a number-average molecular weight of 2500.
Produ~~tion Exam 1e 4 Synthesis of polyester resin a~
-13- 209fi873 To a 2 liter reaction vessel equipped with a stirrer, a thermostat and a condenser, bishydroxyethyl taurin (67 parts), n eopentyl glycol (65 parts), azelaic acid (118 parts), phthali.c anhydride (93 parts) and xylene (27 parts) were charged and heated. Water produced by the reaction was removed by azeotropy with xylene.
The reaction mixture was heated to 190°C over about 2 hours after the beginning of reflux and stirring and dehydration. were continuously conducted until an acid value (corresponding to carboxylic acid) became 72.5, and then cooled to 140°C. With mainta i n; nor a+- i do°r r~,.a", .. r, "
(manufactured by Shell Co.) (157 parts) was added dropwise over 30 minutes and stirred continuously for 2 hours to complete the reaction. Furthermore, dimethylethanolamine (47 parts) and deionized water (1100 parts) were added. The resulting polyester resin had an acid value of 59, a hydroxyl value of 90, a volatile content of 30 % and a number-average molecular weight of 1054.
Production :Example 5 Synthf~sis o:E acrylic resin To the' same reaction vessel as that used in Production Exannple 1,, xylene (700 parts) was charged and heated to 130°C:. Then, a monomer initiator solution of styrene (200 parts), 2-ethylhexyl acrylate (200 parts), hydroxyethyl methacr5rlate (90 parts), methacrylic acid (10 parts), methyl methacrylate (100 parts) and t-butylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 -~;
hours and stirred continuously for 2 hour to obtain an acrylic resin having a volatile content of 45 %, a number-average molecular weight of 5600 and an acid value of 10.
Production Example 6 Synthesis of acrylic resin To the same' reaction vessel as that used in Production Example J., butyl acetate (700 parts) was charged and heated to 130°C. Then, a monomer initiator solution of styrene (200 p,arts), n-butyl acrylate (200 parts), 2-hydroxyethyl methacrylate (90 parts), methacrylic acid (10 parts), methyl methacrylate (100 parts) and t-butylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 hours and stirred continuously for 2 hours to obtain an acrylic resin having a volatile content of 45 0, a number-average molecular weight of 8000 and an acid value of 10.
Produ~~tion Example 7 Synths=sis of acrylic resin To the same reaction vessel as that used in Production Example l, xylene (350 parts) and methoxypropanol (350 parts) were charged and heated to 130°C. Then, a monomer initiator so:Lution of styrene (160 parts), 2-ethylhexyl acrylate (200 parts), hydroxyethyl methacrylate (90 parts), met:hacrylic acid (50 parts), methyl methacrylate (100 parts) and t-but:ylperoxy-2-ethylhexanoate (36 parts) was further added dropwise over 3 hours and stirred continuously far 2 hour to obtain an acrylic resin having a volatile content of 45 %, a number-average molecular weight _~,~, __ -15- 2o~s873 of 5600 and an acid value of 50.
Production Example 8 Pre~~aration 1 of pigment-dispersed paste Acr:~lic resin prepared in Production Example 2 (54 parts), M-1100 manufactured by Cablack Co. (12 parts) and deionized water (1B parts) were subjected to mill dispersion for 3 hours to obtain a pigment paste.
Production Example 9 Pre~~aration 2 of pigment-dispersed paste Acr:~lic resin prepared in Production Example 6 (100 parts) and Maloo ~~-6424 manufactured by Harmon Co. (15 parts) were :subjected to mill dispersion similarly to obtain a pigment paate.
Example 1 Pre~?aration l of aqueous metallic coating composition The acrylic resin of Production Example 1 (170 parts), C-30:3 manufactured by Mitsui Toatsu Chemicals (methylated melamine, solid content: 100 %, 21 parts), aluminum pas~~e (Alpaste~7160N) manufactured by Toyo Aluminum Co. (16.3 parts) and a 50 o xylene solution of lauryl acid phosphate (H7~B: 7.:3) (1.6 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized wai:er and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous metallic coating composition.
f~''~.
16 _ Example 2 Preparation 2 of aqueous coating composition The acrylic resin of Production Example 1 (170 parts), C-30:3 manufactured by M~.tsui ~"oatsu Chemicals (methylated melamine solid content: 100 0, 30 parts), pigment paste M-100 of Production Example 8 (30 parts) and a 50 % xylene solution of stearyl acid phosphate (HLB . 5.5) (2.5 parts) were mixed with stirring by a stirrer.
top coating compocaition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford. cup #4 t;a obtain a.n aqueous coating composition.
Example 3 Preparation 3 of solvent base coating composition The acrylic resin of Production Example 6 (150 parts), U-20N-60 manufactured by Mitsui Toatsu Chemicals Co.
rn~
(butylated melamine), Br:ightcoppe~ manufactured by Marl Co.
(mica, 17 parts), pigment paste Pe~l.indmaloon of 7:~roduction Example 9 (18 parts} and a 50 ~ xylene solution of isostearyl acid phosphate (HLB: 5.~i) (3.2 parts) were mixed with stirring by a stirrer_ An acrylmelamine base coating composition obtained was diluted with a mixture of ethyl acetate and xylene (1:1) and viscosity was adjusted to 30 seconds at 25°C using Ford cup #4 to obtain an acrylmelamine based coating composition.
Example 4 Preparation 4 of aqueous coating composition _1~_ X096873 The F>olyest_er resin of Production Example 4 (180 parts), C-303 manufactured by Mitsui Toatsu Chemicals Co.
(methylated me~lamine~ solid content: 100 0, 25 parts), pigment paste M-1100 of Production Example 8 (16.3 parts) and a 50 o xylene sc>lution of lauryl acid phosphate (HLB:
7.3) (2.5 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous coating composition.
E_ xample 5 Preparation 5 of aqueous metallic coating composition The acrylic resin of Production Example 1 (170 parts), U-20N-60 manufactured by Mitsui Toatsu Chemicals (butylated melamine, 20 parts), a blocked isocyanate compound obtained by blocking isophorone diisocyanate with methyl ethyl ketone (10 parts), aluminum paste (Alpaste 60-600) manufactured by Toyo Aluminum Co. (16.3 parts) and a 50 % xylene solution of 2-ethylhexyl acid phosphate (HLB: 9.2) (2.4 parts) were mixed with stirring by a stirrer.
A top coating composition obtained was diluted with deionized water and viscosity was adjusted to 30 seconds at 20°C using Ford cup #4 to obtain an aqueous metallic coating composition.
Production Example 10 Preparation 1 of clear coating composition The acrylic resin of Production Example 5 (80 parts) and U-~20N-60 manufactured by Mitsui Toatsu Chemicals Co. (butylated melamine, 15 parts) were mixed with stirring by a stirrer.
A acrylmel.amine based clear coating composition obtained was diluted with a mixture of Solvesso 100 and Solvesso 150 (1:l) and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acrylmelamine based clear coating' composition.
Production Example 11 PreF~aration 3 of clear coating composition The acrylic resin of Production Example 7 (500 parts), epoxy group-containing resin of Production Example 3 (100 parts) and a 20 % ethanol solution of tetrabutylamm.onium bromide (7 parts) were mixed with stirring by a stirrer.
An acid epoxy curable based clear coating composition obtained was diluted with a mixture of Solvesso 100 and Solvesso 150 (1:1) and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acid epoxy based clear coating composition.
Production Example 12 Preparation 4 of clear coating composition The acrylic resin of Production Example 5 (50 parts), C-303 manufactured by Mitsui Toatsu Chemicals Co.
(methylated melamine solid content: 100%, 20 parts), a blocked isocyanate compound obtained by blocking isophorone diisocyanate with methyl ethyl ketone (20 parts) and a 5 0 xylene solution of dibutyltin dilaurate (0.6 parts) were mixed with stirring by a stirrer.
An acryl-melamine-isocyanate based clear coating composition obtained was diluted with Solvesso 150 and viscosity was adjusted at 20°C for 22 seconds using Ford cup #4 to obtain an acryl-melamine-isocyanate based clear coating composition.
Comparative Example 1 According to the same manner as that described in Example 1 except f or adding ethyl acid phosphate (HLH value:
15.4) in place of lauryl acid phosphate, an aqueous metallic coating composition was obtained.
Comparative Exam 1e 2 According to the same manner as that described in Example 1 excerpt for adding laurylpolyoxyethyl acid phosphate [HLB value of 12.1 (n=4) and HLB value of 13.5 (n=6)] in place of lauryl acid phosphate, an aqueous coating composition was obtained.
Comparative Example 3 According to the same manner as that described in Example 1 excel?t for adding a reaction product of bisphenol A type epoxy resin having a molecular weight of 400 with phosphoric acid in place of lauryl acid phosphate, an aqueous coating composition was obtained.
Comparative Example 4 According to the same manner as that described in Example 1 except for adding a 50 o xylene solution of lauryl acid phosphate (0.1.6 parts), an aqueous coating composition was obtained.
Comparative Example 5 According to the same manner as that described in Example 1 except for adding a 50 g xylene solution of lauryl acid phosphate (16 parts), an aqueous coating composition was obtained.
Exam 1p a 6 Coat forming method ("two coat-one bake" method) A coating composition obtained in Example 1 was air sprayed on a intercoated steel plate which is not subjected to sanding su~:h that a thickness of a dry coat became y. After ;setting for 5 minutes, the coated plate was 15 preheated at 130°C for 5 minutes and a coating composition obtained in P~~oduction Examples 10 to 12 was air sprayed such that a thickness of a dry coat became 40 u. After setting for 7 minutes, the coated plate was dried at 140°C
for 20 minute:>. Adhesion of the obtained coat was evaluated. The combination of the base coat with the clear coat as well as the results of adhesion are shown in Table.
1.
...n, 0 0 0 o c~ 0 0 o c o w a 0 0 0 0 o c. 0 0 0 0 o c a .,, .-, .-~ ..~ .-, ...~ .~ ..-. .~ .~ .--. ~a w ~ ~. w ~ ~ ~ w n~
d O O O O Cwf'1 op 00 O O N ~5.,"
.G O O O O C~ .~ .-1 ~ L
'D .-~ .--~ .-I .--1 .-~
N C
QI
O E
m N
C y~
O O O O .-i cv'I N N N N N O
~.a .--1 .-i .-1 r--i ...~ .--~ .-~ .-1 .--I .-H U N
iJ
..a N ~ d O 0~~ N 4J Gl N C1 O
M r-1 ,-I .-a r1 .-i .~ ,-1 ~ -.-a .-a O n-d O GL GL 0. G. C~ G1 f3. L1 GL 0. .~ t0 ca. E E E E E' E E E E E a E m m ~o w ai co cn m m ~ E ~.~
o x x x x x', x x x x x U w w w w w w w w w w o a~
E
on a G c c c. c G a c a a C O O O O G O O O O O O G
.,..r .,.~ .,..~ .,q .,.~ .,.,~ .,~ .,..~ .,.~ .,.q .,..
iJ L J-1 .N J..1 J-~ 1J L 1J JJ JJ N
0 o a n a a a o 0 0 ~ H
U 'O Tl 'D Tl ~i 'O 'O 'C 'D 'O
O O O O C O O O O O N
Y~ ~ Y~ ~ Y~ ~i ~
c0 Pa GL Aa pa GL C1~ G1 GL W C4 W N
d O G.
U ,~ L
of of 1r m G d OD L
O L C a C ..-1 U
L
O O
G O
O ~p .b .-.~
CL ~ N M wT ~~ .-~ N M v? U'1 N
E y~ m ya O N N CY d a~ d O d N N td U N
U ~ e-1 ~ r-1 .-i .-I .-a ~-1 .-I e-1 J O.
G. CL a. G. p4 GL G. GL G. 0. s.~ 't7 0o E E E E E E E E E E a c L
c m ~a m co ai cc m ca ~ ~a a o 0 x x x x x' x x x x x v v w w w w w w w w w w m ~ ~ b 0 3 ~o a~
v 0. a. a. a. a. 3 .-~
E E E E E a~ a~
a~ 0 0 0 0 0 ~ ~ v m U U U U U ~C m 0.
d 1 0. L C
O
a .--~ C
m d d ~
a a w C, c0 O
0. ~ N M wt u~, ~D t~ 00 O~ O
~i r L
N
d H
Exam~~le 7 Coat forming method A bare coating composition prepared in Examples 1 to 5 and Comparative Examples 1 to 5 was applied on an intercoated steel plate such that a thickness of a dry coat became 15 u. After setting for 5 minutes and preheating at 80°C for 5 minutes, a clear coating composition of Production Examples 10- to 12 was applied on the coated plate such that a thickness of a dry coat became 40 u, followed by setting for 10 minutes. The coated plate was baked at 160°C
for 18 minute~a by a drier to make a test plate.
The test p:Late was recoated with the same base coating compo~~ition and clear coating composition without sanding and baked at. 140°C for 18 minutes to form a two coat-one bake coat consists of 4 layers. Recoat adhesion of the coat was evaluat:ed. The combination of the base coating composition with the' clear coating composition as well as the results of recoat adhesion are shown in Table 2.
....
>~
O
m d O O O O O O O O O O
.c O O O O O O O O O O
O O O a0 ~r1 ~W n c0 a N
1~ O O~ Ov O~ CT .r O
U
d G
0000~-~cVNNNNN
~.-I .-1 .--~ .--~ .--1 ~-~ .-1 .--1 .-H .-i .-~
~.i v ~ ~ U ~y N d 4J N N
m .-a .-r .--i ~ ~a .-a ~ ,~ .-a .-.1 O C1. p. Q. p, ~2, C3. G1 C1 f~ G, 0.EEEE1'-__EEEEE
E m w co ce ~~ ~n <o m m of o x x x x ~~e x x x x x U W W W W W W W W W W
00 C C C G f~ G G G C G
G O O O O O O O O O O
"'~ .r1 .r-I ~.i ..y ..1 .r1 ....a .,..~ .,..~ "-1 JJ 1-~ Y.~ 1J ii 1.J L yJ L y! y1 ~O U U V U U U U U U U
O a a a a :~ a a a a a U 'p ~O 'L7 'C '17 "O '~ 'O 'O 't7 O O O O O O O O O O
i~ Ya S.n y.. f, 1w 1, l, S. la 1a W G.n CL GL C4 G.>~ CL W Pr f1n U
!~
O
a~
m O
(~. .-I N n'W T V1 .--i N t~7 T V1 E
o a> d C~ a~ w d n~
U n--i e-1 v--1 ,~ ~i r-1 r-1 ~ '-1 r-I
FL A» LL GL C1 C1. Q. C1 GL A.
aD E E E E F. E E E E E
G m ~ ~n ~ ca co m x x x x x x x x x x w w w w w w w w w w U Q. GL 41 G1 Q.
O O O O O
m U U U U U
d L1 .~ N cy? ~rwD r~ 00 O~ O
L
m d E~
Claims (4)
1. A process for forming a coating composite on a substrate, comprising the steps of:
forming on the substrate a cured film composed of a first base coat layer and a first clear coat layer formed on the first base coat layer, applying a second base coating composition on said cured film without sanding the cured film, applying a second clear coating composition thereon without curing the second base coating composition and then baking to cure simultaneously the second base coating composition and tine second clear coating composition, wherein both said second base coating composition and a first base coating composition which forms said first base coat layer comprises:
(A) a film-forming resin, (B) a crosslinking agent for thermosetting the resin (A), and (C) a phosphate, a sulfonic acid or a carboxylic acid having a long-chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12, wherein a solid content of the component (C) is 0.1 to 5 % by weight based on a total solid content of the components (A) and (B).
forming on the substrate a cured film composed of a first base coat layer and a first clear coat layer formed on the first base coat layer, applying a second base coating composition on said cured film without sanding the cured film, applying a second clear coating composition thereon without curing the second base coating composition and then baking to cure simultaneously the second base coating composition and tine second clear coating composition, wherein both said second base coating composition and a first base coating composition which forms said first base coat layer comprises:
(A) a film-forming resin, (B) a crosslinking agent for thermosetting the resin (A), and (C) a phosphate, a sulfonic acid or a carboxylic acid having a long-chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12, wherein a solid content of the component (C) is 0.1 to 5 % by weight based on a total solid content of the components (A) and (B).
2. The process according to claim 1, wherein said film-forming resin (A) is an aqueous resin containing an amide group.
3. The process according to claim 1, wherein said film-forming resin (A) is are acryl resin prepared by polymerizing 5 to 40 % by weight of amide group-containing ethylenic monomers, 3 to 25 % by weight of acide group-containing ethylenic monomers and other copolymerizable ethylenic monomers.
4. The process according to any one of claims 1 to 3, wherein said component (C) is a phosphate having a long-chain alkyl group of 8 to 18 carbon atoms and HLB of 3 to 12.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP133380/1992 | 1992-05-26 | ||
| JP13338092 | 1992-05-26 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2096873A1 CA2096873A1 (en) | 1993-11-27 |
| CA2096873C true CA2096873C (en) | 2004-07-06 |
Family
ID=15103384
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002096873A Expired - Lifetime CA2096873C (en) | 1992-05-26 | 1993-05-25 | Coating composition having improved intercoat adhesion, its use and multi-layer coating composite |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0571977B1 (en) |
| AU (1) | AU658736B2 (en) |
| CA (1) | CA2096873C (en) |
| DE (1) | DE69320404T2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5977228A (en) * | 1997-06-26 | 1999-11-02 | S. C. Johnson Commercial Markets, Inc. | Plasticized aqueous coating compositions |
| DE10138126A1 (en) * | 2001-08-03 | 2003-02-27 | Henkel Kgaa | Binder component for surface coating agents with improved adhesive properties |
| US6822040B2 (en) | 2001-09-25 | 2004-11-23 | Basf Corporation | Basecoat composition with improved repair properties |
| EP1819789B1 (en) | 2004-10-20 | 2011-06-15 | Valspar Sourcing, Inc. | Coating compositions for cans and methods of coating |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3992338A (en) * | 1974-08-21 | 1976-11-16 | E. I. Du Pont De Nemours & Company | Coating compositions containing an aminoplast resin and an alkyl acid phosphate curing agent |
| US5147453A (en) * | 1987-11-03 | 1992-09-15 | Basf Corporation | Paint compositions containing silver metal flake pigment |
| CA2014539C (en) * | 1989-04-17 | 2000-07-25 | Shinichiro Umeda | Water borne metallic coating composition |
| US5281443A (en) * | 1991-12-20 | 1994-01-25 | Basf Corporation | Coating method for one-component blocked isocyanate-crosslinked clearcoat |
-
1993
- 1993-05-24 AU AU38752/93A patent/AU658736B2/en not_active Expired
- 1993-05-25 CA CA002096873A patent/CA2096873C/en not_active Expired - Lifetime
- 1993-05-26 EP EP93108500A patent/EP0571977B1/en not_active Expired - Lifetime
- 1993-05-26 DE DE69320404T patent/DE69320404T2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0571977B1 (en) | 1998-08-19 |
| AU3875293A (en) | 1993-12-02 |
| DE69320404T2 (en) | 1999-02-04 |
| EP0571977A3 (en) | 1994-09-21 |
| DE69320404D1 (en) | 1998-09-24 |
| CA2096873A1 (en) | 1993-11-27 |
| AU658736B2 (en) | 1995-04-27 |
| EP0571977A2 (en) | 1993-12-01 |
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